
/* Copyright 1998 by the Massachusetts Institute of Technology.
 * Copyright (C) 2004-2009 by Daniel Stenberg
 *
 * Permission to use, copy, modify, and distribute this
 * software and its documentation for any purpose and without
 * fee is hereby granted, provided that the above copyright
 * notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting
 * documentation, and that the name of M.I.T. not be used in
 * advertising or publicity pertaining to distribution of the
 * software without specific, written prior permission.
 * M.I.T. makes no representations about the suitability of
 * this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 */

#include "ares_setup.h"

#include "ares.h"
#include "ares_library_init.h"
#include "ares_private.h"

/* library-private global and unique instance vars */

#ifdef USE_WINSOCK
fpGetNetworkParams_t ares_fpGetNetworkParams = ZERO_NULL;
fpSystemFunction036_t ares_fpSystemFunction036 = ZERO_NULL;
fpGetAdaptersAddresses_t ares_fpGetAdaptersAddresses = ZERO_NULL;
#endif

/* library-private global vars with source visibility restricted to this file */

static unsigned int ares_initialized;
static int ares_init_flags;

/* library-private global vars with visibility across the whole library */
void* (*ares_malloc)(size_t size) = malloc;
void* (*ares_realloc)(void* ptr, size_t size) = realloc;
void (*ares_free)(void* ptr) = free;

#ifdef USE_WINSOCK
static HMODULE hnd_iphlpapi;
static HMODULE hnd_advapi32;
#endif

static int ares_win32_init(void)
{
#ifdef USE_WINSOCK

    hnd_iphlpapi = 0;
    hnd_iphlpapi = LoadLibraryW(L"iphlpapi.dll");
    if (!hnd_iphlpapi)
        return ARES_ELOADIPHLPAPI;

    ares_fpGetNetworkParams = (fpGetNetworkParams_t)
        GetProcAddress(hnd_iphlpapi, "GetNetworkParams");
    if (!ares_fpGetNetworkParams) {
        FreeLibrary(hnd_iphlpapi);
        return ARES_EADDRGETNETWORKPARAMS;
    }

    ares_fpGetAdaptersAddresses = (fpGetAdaptersAddresses_t)
        GetProcAddress(hnd_iphlpapi, "GetAdaptersAddresses");
    if (!ares_fpGetAdaptersAddresses) {
        /* This can happen on clients before WinXP, I don't
         think it should be an error, unless we don't want to
         support Windows 2000 anymore */
    }

    /*
   * When advapi32.dll is unavailable or advapi32.dll has no SystemFunction036,
   * also known as RtlGenRandom, which is the case for Windows versions prior
   * to WinXP then c-ares uses portable rand() function. Then don't error here.
   */

    hnd_advapi32 = 0;
    hnd_advapi32 = LoadLibraryW(L"advapi32.dll");
    if (hnd_advapi32) {
        ares_fpSystemFunction036 = (fpSystemFunction036_t)
            GetProcAddress(hnd_advapi32, "SystemFunction036");
    }

#endif
    return ARES_SUCCESS;
}

static void ares_win32_cleanup(void)
{
#ifdef USE_WINSOCK
    if (hnd_advapi32)
        FreeLibrary(hnd_advapi32);
    if (hnd_iphlpapi)
        FreeLibrary(hnd_iphlpapi);
#endif
}

int ares_library_init(int flags)
{
    int res;

    if (ares_initialized) {
        ares_initialized++;
        return ARES_SUCCESS;
    }
    ares_initialized++;

    if (flags & ARES_LIB_INIT_WIN32) {
        res = ares_win32_init();
        if (res != ARES_SUCCESS)
            return res; /* LCOV_EXCL_LINE: can't test Win32 init failure */
    }

    ares_init_flags = flags;

    return ARES_SUCCESS;
}

int ares_library_init_mem(int flags,
    void* (*amalloc)(size_t size),
    void (*afree)(void* ptr),
    void* (*arealloc)(void* ptr, size_t size))
{
    if (amalloc)
        ares_malloc = amalloc;
    if (arealloc)
        ares_realloc = arealloc;
    if (afree)
        ares_free = afree;
    return ares_library_init(flags);
}

void ares_library_cleanup(void)
{
    if (!ares_initialized)
        return;
    ares_initialized--;
    if (ares_initialized)
        return;

    if (ares_init_flags & ARES_LIB_INIT_WIN32)
        ares_win32_cleanup();

    ares_init_flags = ARES_LIB_INIT_NONE;
    ares_malloc = malloc;
    ares_free = free;
}

int ares_library_initialized(void)
{
#ifdef USE_WINSOCK
    if (!ares_initialized)
        return ARES_ENOTINITIALIZED;
#endif
    return ARES_SUCCESS;
}
